Lift and delivery pump



March 10, 1970 L. R. CZERMAK 3,499,392

LIFT AND DELIVERY PUMP Original Filed March 6, 1967 2 Sheets-Sheet 1 March 10, 1970' L. R. CZERMAK LIFT, AND DELIVERY PUMP Original Filed March 6, 1967 Fig.5 1

2 Sheets-Sheet 2 United States Patent 3,499,392 LIFT AND DELHVERY PUMP Leo R. Czermak, 13 Anichstrasse, 6020 Innsbruck, Austria Continuation of application Ser. No. 620,919, Mar. 6, 1967. This application Feb. 7, 1969, Ser. No. 800,033 Claims priority, application Austria, Mar. 17, 1966, A 2,529/66 int. Cl. F041) 1/02, 7/04 U.S. Cl. 103171 17 Claims ABSTRACT OF THE DISCLOSURE In a pump with two coaxially aligned cylinders and an intermediate casing with the inlet and outlet ducts, the two pistons in the respective cylinders are interconnected by a piston rod which extends through a centrally located outlet passage of the casing, the outlet passage being in communication with the outlet duct. The corresponding inlet passage of the casing is located radially outward of the outlet passage. Inside the casing the two mouth openings of the central outlet passage are surrounded by respective coaxially spaced valve seats which face each other and of which one at a time is engaged by movable valve closure means seated and axially displaceable on the piston rod within the outlet passage of the casing. Preferably the two mouths of the inlet passage have an arcuate shape and are located on the same axially opposite sides of the casing as the respective mouths of the outlet passage and are controlled by annular valvedisk members which coaxially surround the cylinder axis and of which one member at a time is pressed from the outside against the casing to thus close the inlet passage toward one of the cylinders. The two cylinders are thus alternately connected to the inlet and outlet ducts.

This application is a continuation of 620,919, filed Mar. 6, 1967, now abandoned.

This invention relates to a lift and delivery pump with two coaxially aligned cylinders on opposite sides of a casing which has valve-controlled inlet and outlet passages for the medium to be pumped. The two pistons in the respective cylinders are connected by a piston rod passing through the casing; and the two cylinder chambers adjacent to the pistons vary their respective volumes in mutually inverse relation as these chambers are alternately connected with the inlet and outlet passages.

A known pump of this type serves the purpose of pumping a liquid. It is stationary and comprises two inlet and outlet valves disposed in the casing with shaft arrangements of usual construction, which are opened and closed by the moving agent. If these valves are pushed to their closing position by coordinated valve springs, a strong negative pressure is produced by repeating the aspiration of air or gas since, even if the moving gaseous agent is not able to take along the valves, the latter are pushed to their closing position immediately after reversal of the piston strokes, so that a return flow of the agent is precluded. However, it is complicated and expensive to provide the valves with valve shafts and springs and much space is needed to provide for sufficient passage position in time also without any valve springs in such manner that a strong negative pressure is produced by repeating the aspiration of air or gas and a liquid can thus be drawn in from a great depth. A pump of this type will also be suitable for pumping a liquid from a high-level receptacle like a siphon, so that the liquid, after initial aspiration, will continue flowing through the device without further pumping. It shall be constructed in such manner that it is easy to stop and re-open the flow of the agent and that the agent is capable of returning from the outlet to the inlet. It shall form a simple unit closed upon itself in such a manner that no bores leading outwards nor conduits outside the cylinder are required for the pressure balance of the outer cylinder chambers.

According to the invention these objects are attained by having the passage coordinated to the outlet pass centrally through the casing coaxially around the piston rod, While the passage coordinated to the inlet passes through the casing in a zone outwardly adjacent to the passage coordinated to the outlet. Both axially opposite sides of the outlet passage are provided with an inwardly facing valve seat around the outlet mouth against which a one-part or multiple-part outlet valve, displaceably seated on the piston rod between the two valve seats, is pushed to its closing position. The passage coordinated to the inlet preferably embraces the passage coordinated to the outlet, and has respective months at the front sides of the valve casing preferably provided with annular inlet valves.

In a preferred embodiment of the invention the outlet valve comprises two valve disks and a tube piece coaxially seated on the piston rod between the two disks, and a recess in the piston rod is coordinated at least to one of the two valve disks and, at the beginning of the compression stroke of the piston adjacent to this valve disk, bypasses the closing position of said valve disk in such manner that the adjacent inlet valve is immediately pushed to its closing position on account of the pressure drop directed from the outlet to the inlet. The recess on the piston rod can be avoided, if according to the invention the valve disk of the outlet valve is slack on the piston rod, which permits the connection of the chambers lying on each side of the latter in its final position, and if the tube piece, owing to its sufficiently large frontal area, tightly rests against this valve disk in the closing position of the outlet valve. In both embodiments and in another preferred embodiment of the invention, a maximum of free air capacity is obtained. In the latter embodiment, a recess is provided between at least one of the two valve disks of the outlet valve and the piston rod, a connecting piece passing through said recess is rigidly connected either with the tube piece tightly seated on the piston rod between the two valve disks or with the other valve disk of the outlet valve tightly seated on the piston rod; and the free end of the connecting piece is provided with a stop for moving the inlet valve adjacent to this end to its opening position.

The passage of fluid medium through the device is stopped when, in the inner end position of one of the two pistons, the latter maintains the adjacent inlet valve closed and a stop on the piston rod also maintains the non-adjacent one of the outlet valves closed.

The return flow of the agent is permitted by the fact that in a certain position of the piston rod 2. connection is established between the outlet and the inlet through an opening between the piston rod and outlet valve disk then in its closing position.

As a unit closed upon itself, the device has a hollow piston rod which connects the two outer cylinder chambers with each other, or the piston rod connects each of 3 the outer cylinder chambers with the opposite inner one by means of two longitudinal bores respectively.

Further details of the invention are hereinafter described with reference to the figures of the accompanying drawings although the invention is not limited to the embodiments described.

FIGURE 1 illustrates an embodiment of the invention in longitudinal section on the line C-D of FIGURE 2;

FIGURE 2 illustrates the same embodiment in section on the line AB f FIGURE 1;

FIGURE 3 demonstrates a special embodiment of the outlet valve;

FIGURE 4 illustrates another embodiment of the invention in longitudinal section, the cylinders and the piston rod not being represented, the sectional plane passing through the axis of the device and the axis of a distance pin resting in the casing.

FIGURE 5 shows another embodiment of the invention by a longitudinal section on the line C-D of FIG- URE 6;

FIGURE 6 is a cross section on the line AB of FIG- URE 5;

FIGURE 7 is a sectional view in elevation of the right inlet valve of this embodiment seated on the piston rod;

FIGURE 8 illustrates another embodiment of the invention in longitudinal section, the cylinders and the piston rod only partially being represented.

FIGURE 9 illustrates a particularly simple embodiment of an outlet valve.

According to the embodiment represented in FIG- URES 1 and 2, the pump comprises two axially disposed cylinders 1 and 2, which are provided, each, with a cover 1a and 2a and which are tightly attached to a casing 3 connecting the cylinders. The casing has a cylindrical outer shape and is rigidly connected with two radially spreading nipples 3a and 3b forming the inlet 4 and the outlet 5. A piston rod 10 connects the two pistons 11 and 12 in such manner that they are displaceable in the cylinders 1 and 2, and continues in a connecting rod 13 which passes through the cylinder cover 2a, its end being provided with a handle 14. The piston rod is hollow; one of its ends freely opens into the left outer cylinder chamber 15 and its other end opens into the right outer cylinder chamber 16 through two radial bores 13a disposed in the equally hollow connecting rod 13 closely behind the piston 12 in such manner that the two outer cylinder chambers are connected with each other for pressure balance.

The passage 9 coordinated to the outlet 5, through which passes the piston rod 10, extends centrally through the casing 3 in direction of the piston rod and is provided, around each of the two circular outlet mouths, with a sectional narrowing in the form of a valve seat against which the outlet valve 170d, displaceable on the piston rod, tightly abuts in its two closing positions. The outlet valve consists of two valve disks 17b and 17d and a tube piece 170 tightly seated on the piston rod between the latter. For each of the valve disks there is provided an annular groove 1012 or 10d in the piston rod 10. Each groove is sloped on both sides for the guidance of the outlet valve; in the closing position of valve disk 17b or 17d, if the piston rod is in its left or right final position, said annular groove 1% or 1 0d projects away from the valve disk in direction of the adjacent cylinder chambers 6 or 7. The tube piece 170 has such a length that the outlet valve 17bcd, in each of its two closing positions, comprises the piston rod in such a length that the annular groove 10b or 10d is at most opened towards one of the chambers lying on both sides of the outlet valve. Between the outlet valve and the piston 12, a distance tube 18a is provided on the piston rod of such a length that this piston, in its inner final position, as illustrated in FIGURE 1, maintains the outlet valve in its left closing position through the distance tube.

The passage 8 coordinated to the inlet 4 having an annular sector-shaped cross section passes through the casing 3 in the zone adjacent to the outlet passage 9. The ends or mouths of the inlet passage form an annular sector-shaped groove in the front sides of the casing, the arcuate ends of the annular sector-shaped mouths being denoted by 8a and 8b. These mouths are opened and closed towards the cylinder chambers 6 and 7 by inlet valves 19 and 21, each having the form of an annular valve disk. Each of the inlet valves displaceably rests in a short bore 6a or 711, continuing a cylinder bore with somewhat larger diameter and serving as a guide; the inlet valves find one of their final positions on a front side of the casing 3, their other final position'on the front side of the cylinder 1 or 2.

Between the inlet valve 19 and the piston 12, as illustrated in section in the embodiment according to FIG- URE 4, a distance pin 2% provided with a collar in its middle zone is easily displaceable in an axial bore 20a of the casing in such manner that its collar, in the left final position, abuts against a constriction of the bore 20a and, in the right final position, abuts against the inlet valve 21 through the recess 21]) of which grips the part of the distance pin at the right of the collar. The pin 20b has such a length that the piston 12, acting through the pin, maintains the inlet valve 19 open from shortly before until shortly after the piston 12 occupies its illustrated innermost position.

An elastic ring baffle 1117 or 12b is connected with each of the pistons 11 and 12. It serves the purpose of damping the stroke of the piston 11 or 12 in its inner final position and, 011 account of its elasticity, maintains that inlet valve 19 or 21 tightly onto its seat in this position of the piston 11 or 12.

The inlet nipple 3a has an annular bulge at its end over which the hose end is pushed. A guard ring 30 provided with an internal thread clamps the hose end to prevent the hose from being drawn off.

If in the pump described, starting from a position as illustrated in FIGURE 1, the pistons 11 and 12 are pushed to the right by the piston rod 10 and the connecting rod 13 by pushing the handle 14 to the right an excess pressure is produced in the cylinder chamber 6 and a negative pressure in the cylinder chamber 7. This pressure difference moves the inlet valve 19 from the left to the right end positionpThe distance pin 2% and the inlet valve 21, as well as the valve disks 17b and 17d of the outlet valve 17bcd whose tube piece is taken along by the piston rod, also move to the right. In the right position, the inlet valve 19 has closed the passage 8 as well as the inlet 4 and the bore in which rests the distance pin 20b, towards the cylinder chamber 6, and the inlet valve 21 has opened the passage 8 as well as the inlet 4 towards the cylinder chamber 7. When the outlet valve 17bcd is in its right final position in the passage 9, the outlet 5 is connected with the cylinder chamber 6 and is separated from the cylinder chamber 7. If the pistons 11 and 12 are pushed further to the righet, an agent, e.g. air, is sucked into the enlarging cylinder chamber 7 through the inlet 4 and the passage 8, and the agent contained in the decreasing cylinder chamber 6 is discharged through the passage 9 and the outlet 5. Upon termination of this suction and compression stroke, the pistons are moved in opposite direction, i.e. to the left. The valves and the distance pin also move to the left, thus reversing the connection of the cylinder chambers with the inlet and the outlet, so that the agent is sucked into the cylinder chamber 6 and discharged from the cylinder chamber 7.

By repeating these simultaneous suction and compres sion strokes, a negative pressure becomes more and more effective in the suction line and in the suction cylinder concerned. As a result, the valve disk of the outlet valve, which is in its closing position, remains in its closing position even after reversal of the piston strokes. In the valve and piston position illustrated in FIGURE 1, it is the valve disk 17b. If the pistons 11 and 12 are moved to the right, i.e. at the beginning of the compression stroke in the cylinder chamber 6, starting from this position, the recess 10b disposed on the piston rod and coordinated to this valve disk 1711, becomes situated under this valve disk, thus connecting the chambers lying on both sides of the latter, since the tube piece 170 disposed between the two valve disks 17b, 17d has been taken along by the piston rod, thus releasing this connection. The air flowing into this cylinder chamber 6 from the outlet 5 through this connection compensates for the negative pressure in this cylinder chamber and moves the inlet valve 151, which takes along the distance pin 2011, into its closing opsition so that, when the pistons are moved further to the right, the pressure further rises in the cylinder chamber 6, thus moving the valve disk 17b into its open position. Subsequently the air is discharged from the cylinder chamber 6 through the passage 9 and the outlet 5. As the piston rod 10 takes along not only the tube piece 170, but also the valve disk 17d until they reach their right final position, i.e. the closing position of this valve disk, the inlet valve 21 is opened on account of the negative pressure now more and more effective in the cylinder chamber 7 as the pistons are further moved to the right, and an agent is sucked through the passage 8 and the inlet 4. Upon termination of this suction and compression stroke the pistons are moved to the left and the action is repeated from the right to the left. The tube piece 17c and the valve disk 1711 are taken along by the piston rod 10 until they reach their left final position and the recess 10d of the piston rod is situated under the valve disk 17d said disk remaining in its closing position. Thus the connection from the outlet 5 to the cylinder chamber 7 is open and the air flowing into the latter moves the inlet valve 21 into its closing position, so that, when the pistons 11 and 12 are moved further to the left, the valve disk 17d is opened and the air is discharged from the cylinder chamber 7, while the air is sucked into the cylinder chamber 6 from the suction line after the valve disk 1712 has come to its closing position and the inlet valve 19 has opened. Upon the aspiration of air or other gaseous agent, a strong vacuum can be produced and thus a liquid can be sucked from a great depth. After it has filled the device, the valves are reversed by the moving liquid immediately after reversal of the piston strokes. The liquid can subsequently be pumped up to a considerable height.

If such a quantity of liquid was sucked from a highlevel receptacle that can continue flowing by itself by the siphon effect, it flows into the passage 8 through the inlet 4 and moves the inlet valves 19 and 21the passage being open-into the position most favorable for the streaming of fluid and, according to the position of the outlet valve 17bcd, it finally flows off through one or both ofthe two cylinder chambers, the passage 9 and the outlet 5 without any pumping.

If the passage is blocked, e.g. in the position of the pistons illustrated in FIGURE 1, the elastic ring bafiie 12a of the piston 12 maintains the adjacent inlet valve 21 in its closing position and also maintains, through the distance tube 18a, the outlet valve 17bcd in its closing position at the outlet valve seat remote from the piston 12, thus interrupting any connection between the outlet and the inlet. In order to open the passage, the handle 14 as well as the piston 12 are moved to the right, thus releasing the s.op for the inlet valve 21 and "the outlet valve 17bcd.

In order to compensate for a vacuum produced in the suction line or to enable the liquid in the riser and in the device to return, a connection must be estabilshed which permits the reflux of a gaseous or liquid medium from outlet to inlet. The distance pin 20b is provided for this purpose. If, starting from the left final position of the pistons 11 and 12 as illustrated in FIGURE 1, the piston rod 10 and at the same time the tube piece 17c are somewhat moved to the right, while the valve disk 17b and the inlet valve 21 are retained in their closing position by the pressure drop directed from the outlet 5 to the inlet 4, the recess Nb of the piston rod becomes situated under the valve disk 1711, thus interconnecting the chambers on both sides of the disk 17!) and thus the outlet 5 with the cylinder chamber 6. The connection from the latter through the passage 8 to the inlet 4 is also open, since the piston 12 maintains the inlet valve 19 open by means of the distance pin 20b.

The lift and delivery pump described according to the FIGURES 1 and 2 can be utilized in any position. In the hand-operated instrument the handle is preferably provided at the top. In this position the inlet valve 21 drops to closing position upon termination of the suction stroke in the cylinder 7. Therefore the recess 10d on the piston rod 10 is not required in order to close this inlet valve in time. In this case a two-part outlet valve can be provided, as illustrated in FIGURE 3. This valve has a valve disk 1% to which the recess 10b is coordinated on the piston rod, and of a valve disk 17d which embraces the piston rod by means of a control device 17a in such a length that the recess 10b, in each of the two closing positions of the outlet valve 17bd, is at most open towards one of the chambers lying on both sides of the latter. The recess 16b is provided with three longitudinal stems for the guidance of the valve disks 17b, 17d.

A device in which the recess between the piston rod and one valve disk of the outlet valve is disposed on the piston rod, as illustrated in FIGURES 1 and 3, presents the following advantage: the tube piece 17c (FIGURE 1), in particular if its ends are conically shaped or if it has a vary small thickness, or the valve disk 17d provided with a control device 17a, while tightly resting against the valve disk coordinated to this recess, being in its closing position, are practically not afliected by the negative pressure in the cylinder chamber adjacent to this valve disk, even if the latter is not tightly seated on the piston rod. Therefore, after reversal of the piston strokes, they are taken along by the piston rod, even if it is particularly easy to displace them on the piston rod. This presents a particular advantage if the device is utilized for slippery liquids.

FIGURE 4 shows another embodiment of the invention. The recess disposed between one valve disk of the outlet valve and the piston rod is provided on the valve disk by having its bore made somewhat larger than the outer diameter of the piston rod. According to FIGURE 4 the valve disk 17]] as well as the valve disk 17d are slack on the piston rod. The tube piece 170, which is displaceable and tightly seated on the piston rod between the latter, is provided with a conical extension at each end in order to center the valve disk 17b or 17d in its closing position. However, the valve disk 17b or 17d may also be centered by providing its =bore with cams by which it glides on the piston rod. A centering can be avoided if the frontal area of the tube piece is sufliciently large to maintain closed the bore of the valve disk eccentrically seated on the piston rod. In order to tightly maintain the outlet valve 17bcd in its closing position at the side facing away from the piston, for the purpose of stopping the passage of medium in the inner final position of the piston 12, as illustrated in FIGURE 4, a fixed stop 18!) is provided on the piston rod 10. Otherwise the device according to FIGURE 4 corresponds to the embodiment illustrated in FIGURES 1 and 2 and functions analogously.

FIGURES 5, 6 and 7 illustrate another embodiment of a pump according to the invention. The cylinders 1 and 2, the pistons 11 and 12, the casing 3 with the inlet 4, the outlet 5 and the passages 8 and 9 coordinated to the latter, and the distance pin 20b have the same form as those in FIGURES 1 and 2. The piston rod 10 connecting the two pistons 11 and 12 is provided with two longitudinal bores separated from each other; one end of one of these bores freely opens into the cylinder chamber 15, the other end opens into the cylinder chamber 7 through a radial bore, while one end of the other bore freely opens into the cylinder chamber 16, the other end opens into the cylinder chamber 6 through a radial bore; thus the outer cylinder chambers 15, 16 are also applied to the pumping action. The connecting rod 13 connecting the piston rod 10 with the handle 14 passes through the cylinder cover 2a. This embodiment is particularly characterized by the fact that each of the two annular inlet valves 19 and 21 is coupled with one connecting piece 190 or 21c through radial stems 19a or 21a in direction of its closing position; said connecting piece passes through the recess disposed between the piston rod 10 and the valve disk 1712 or 17d of the outlet valve 17bcd adjacent to the inlet valve 19 or 21 and is added to the tube piece 170 which is displaceable between the two valve disks of the outlet valve and tightly seated on the piston rod. According to the embodiment the connecting piece 190 or 210 consists of three stems which, at their end turned to the inlet valve 19 or 21, pass over into a ring comprising the piston rod, serving as a stop for the stems of the inlet valve.

If in this pump, starting from the position illustrated in FIGURE 5, the piston rod 10 is moved to the right, it takes along the tube piece 170 seated on it. The latter takes along the valve disk 17d of the outlet valve until the disk reaches its closing position, as well asthrough the connecting piece 19cthe inlet valve 19 which takes along the distance pin 20!) and, in its closing position, closes the passage 8 and the bore for the distance pin towards the cylinder chamber 6. While the piston rod and the pistons 11 and 12 are moved to the right, the pressure rises in the cylinder chambers 6 and 16 and falls in the cylinder chambers 7 and 15. Thus the valve disk 17b of the outlet valve and the inlet valve 21 are opened and on the one hand, the air is subsequently discharged from the cylinder chambers 6 and 16 through the passage 9 and the outlet and on the other hand, the agent is sucked into the cylinder chambers 7 and 15 through the passage 8 and the inlet 4. After reversal of the piston strokes, the action is repeated from the right to the left in an analogous way. By repeating these suetion and compression strokes a strong vacuum can be produced in the suction line and thus a liquid can be sucked in from a great depth and, after filling the device, it can be pumped in any quantity up to a certain height.

The passage in this device is stopped by virtue of the fact that on the one hand, the piston 12, in its inner final position, maintains the inlet valve 21 in its closing position by means of its elastic ring baffle 12b and on the other hand, maintains the valve disk 17b of the outlet valve in its closing position through the intermediary of the tube piece 170 and the connecting piece 210 whose free end abuts against the piston. The reflux of the agent from the outlet to the inlet is obtained substantially as described with reference to the embodiment according to FIGURES 1 and 2, and an analogous siphon action for pumping liquid from a high-level receptacle is also applicable.

FIGURE 8 demonstrates another embodiment of the invention which can be utilized as a hand-operated instrument, the handle being on top so that the inlet valve 21, upon termination of the suction stroke in the cylinder 7, drops by itself into its closing position. In this device, a recess is disposed only between the valve disk 17b of the outlet valve and the piston rod 10 through which passes the connecting piece 190 coordinated to the inlet valve 19. The connecting piece in this embodiment has the form of a tube seated on the piston rod and is added to the valve disk 17d of the outlet valve 50 that the valve disk 17d is displaceable and tightly seated on the piston rod by means of the tube 190. At the right of the valve disk, the connecting tubular piece 190 extends towards the piston 12 in such a length that the latter, in its inner final position, maintains the valve disk 17b in its closing position by the intermediary of the right part of the connecting piece 190 and by means of the valve disk 17d. A collar disposed at the left end of the connecting piece 19c takes along the inlet valve 19 through its stems 19a in direction of its closing position. Somewhat in front of the collar, a second collar is disposed in such manner that, by means of this collar through the intermediary of the connecting piece 190 the piston 12 maintains the inlet valve 19 open through its stems 19a from a short distance efore to a short distance after its internal end position, so that the agent which flows from the outlet 5 through the recess disposed between the valve disk 17b and the piston rod 10 into the cylinder chamber 6, can enter the passage 8 and flow to the inlet 4. In other respects the device func' tions as described above with reference to the other embodiments.

FIGURE 9 illustrates a particularly simple embodiment of an outlet valve. It only consists of one valve disk 17. A recess 100 on the piston rod 10 is coordinated to the valve disk for bypassing the closing position of the disk in one of its final positions. Regarding its other final position, a further recess can be coordinated on the piston rod.

If neither a maximum of free air capacity nor a reflux of the agent through the device are required, a recess between the piston rod and one valve disk of the outlet valve can be avoided. The functioning of a lift and delivery pump, in which such a recess is not provided, results in an analogous way from what has been explained above relative to the embodiments described with reference to the accompanying drawings.

The devices can be provided with inlet valves to which pressure springs are coordinated, such a spring being preferably disposed between the back side of the inlet valve 19 or 21 and the front side of the cylinder 1 or 2. Between the two valve disks 17b and 17d of the outlet valve 17bd a pressure spring can equally be provided. Thus all valves of the device can be moved into their closing position by means of their coordinated pressure springs immediately upon termination of a suction stroke.

The casing 3 of the device can be reinforced by a midwall (see FIGURE 6). The wall 80 vertically extends towards the axis of the device in the middle zone of the inlet passage 8 from both ends of the latter toward the outlet 5, partially embracing the outlet passage 9, somewhat toward the inlet 4, preferably tapering in the form of a wedge.

At their front sides the pistons may be provided with a support of rubberlike elasticity instead of a ring battle of ebonite-like elasticity. The seat-engaging surfaces of the movable valve members as well as their fixed seat surfaces at the casing may be provided with a support of rubberlike elasticity. If the movable valve members themselves are made of a material of ebonite-like elasticity, they can have a thickness of a few tenths of millimeter only, in such manner that they tightly rest against their seats to compensate for elasticity.

In the embodiments described, the pump is provided with an inlet nipple 3a and an outlet nipple 3b, which are radially disposed on the casing 3, one diametrically opposite each other. However, the nipples may also enclose a smaller angle and may deviate from the radial direction in the casing. Several inlet and outlet nipples may be provided. The nipples may be interchangeable and have a different inside diameter. A stop means of any desired construction can be connected with the casing instead of a nipple. It is also possible to incorporate a stop means into a duct or to secure it to the end of the latter.

The pumps may be provided with or without a reflux device or with or without a device for stopping the passage of medium. The piston rod can be solid; in this case the two outer cylinder chambers can be connected with eachother through a suitable device for pressure balance or may freely open toward the outside.

The embodiments described illustrate the pump according to the invention as a portable hand-operated instrument. It may also be stationary. In this case the connecting rod 13 of the device is preferably connected with a lever to which several devices may be added. The pump is hand-operated or motor driven. If driven by a motor, the connecting rod is preferably operated by an eccentric. If several devices are operated together, the coordinated eccentrics are disposed in reverse order to each other.

The lift and delivery pump according to the invention thus presents essential advantages as against the known pumps. It is a practical and economic advantage that its construction is simple and handy and that it may be made of acid-resistant plastic, e.g. hard-PVC or the like; owing to its simple construction, its manufacture avoids waste. It is important that the pump may be constructed in a simple manner as a unit closed upon itself, which highly increases operating reliability, especially if aggressive liquids are pumped. By virtue of the easily and rapidly movable valves the uniformity in raising liquids is hardly affected by the reversal of the strokes.

The lift and delivery pump according to the invention meets manifold requirements as a hand-operated instrument and a siphon, since it is easy to stop and re-open its passage and it is possible for the agent to return. It may also be utilized in many cases as a stationary, hand-operated or motor driven instrument and may be incorporated into another unit on account of its high capacity in comparison to its small size and simple construction.

What is claimed is:

1. A lift and delivery pump comprising two coaxially aligned cylinders, a casing structure interposed between and fixedly joined with said two cylinders and having an inlet and an outlet for the medium to be pumped, two pistons axially displaceable in said respective cylinders and forming therewith respective cylinder chambers adjacent to said casing structure, a piston rod interconnecting said two pistons for conjointly reciprocating them in said cylinders, said casing structure forming separate inlet and outlet passages through which said two cylinder chambers are connectible with said inlet and outlet respectively, inlet valve means and outlet valve means for controlling said passages to alternately connect said chambers with said inlet and outlet respectively, said outlet passage being located centrally in said casing structure and extending axially straight through said structure, said inlet passage being spaced in a radially outward direction from said output passage, said piston rod extending through said centrally located outlet passage in throughout radially spaced relation to said structure, said outlet valve means having two fixed and coaxially spaced valve seats facing each other inside said casing structure and surrounding said outlet passage at respective localities near said two cylinder chambers, and movable valve closure means seated and axially displaceable on said piston rod within said outlet passage and between said two seats for selectively engaging said seats to close one of said respective cylinder chambers relative to said outlet depending upon the stroke direction of said pistons.

2. In a pump according to claim 1, said outlet passage of said casing structure having two central circular mouths coaxially located at said respective cylinder chambers, said inlet passage having two arcuate mouths located at said two cylinder chambers in concentric relation to said respective central mouths, and said inlet valve means comprising two annular closure members coaxially disposed in front of said respective arcuate mouths and movable into and out of engagement with said casing structure for selectively closing one of said respective cylinder chambers relative to said inlet.

3. In a pump according to claim 1, said axially displaceable outlet-valve closure means on said piston rod comprising two valve disks engageable with said respective valve seats, and spacer means disposed on said rod between said two disks for maintaining them axially separated from each other.

4. A pump according to claim 1, comprising bypass means formed between said piston rod and said movable outlet-valve closure means and controllable by movement of said rod, said bypass means forming at the beginning of the compression stroke of said rod a temporary communication between said outlet and the cylinder chamber then adjacent to the closed closure means, whereby the initially negative pressure in said latter chamber keeps said closure means closed while medium passing through said bypass reduces said negative pressure.

5. In a pump according to claim 1, said axially displaceable outlet-valve closure means on said piston rod comprising two valve disks engageable with said respective valve seats, and spacer means disposed on said rod between said two disks for maintaining them axially separated from each other, said piston rod having a recess which, during displacement of said outlet-valve closure means relative to said piston rod at the beginning of the compression stroke, forms a temporary bypass between said outlet passage and the cylinder chamber adjacent to the then closed valve disk, whereby the initially negative pressure in said latter chamber keeps said disk closed and medium returning into said chamber through said bypass reduces said negative pressure.

6. In a pump according to claim 1, said axially displaceable outlet-valve closure means on said piston rod comprising two valve disks engageable with said respective valve seats, at least one of said disks forming a bypass opening adjacent to said piston rod, and means on said rod for closing said bypass due to axial displacement of said rod so as to form at the beginning of the compression stroke a temporary bypass communication between said outlet and the cylinder chamber then adjacent to the closed closure means, whereby the initially negative pressure in said latter chamber keeps said closure means closed while medium passing through said bypass reduces said negative pressure.

7. In a pump according to claim 1, said axially displaceable outlet-valve closure means on said piston rod comprising two valve disks engageable with said respective valve seats, and spacer means disposed on said rod between said two disks for maintaining them axially separated from each other, said inlet valve means comprising two closure members coaxially movable into and out of engagement with said casing structure for selectively closing one of said respective cylinder chambers .relative to said inlet, at least one of said outlet valve disks having a recess, a connecting piece passing through said recess and being axially displaceable by the piston in one of said cylinder chambers, said connecting piece forming a stop engageable with the inlet-valve closure member for said other cylinder chamber to hold said latter closure member in the open position when said latter piston is in its end position close to said casing structure.

8. In a pump according to claim 1, the piston in at least one of said cylinder chambers having stop means, and connecting means mounted on said piston rod in connection with said movable closure means of said outlet valve means and engageable by said stop means for holding said closure means in closed position relative to said other chamber when said piston is in its end position at said casing structure in said one chamber.

9. In a pump according to claim 2, said piston rod having stop means engageable with said closure members of said outlet valve means, and having stop means engage able with said respective closure members of said inlet valve means, said stop means being arranged to promote closing and opening respectively of said inlet and outlet valve means due to the pressure alternately occurring in said respective cylinder chambers.

10. In a pump according to claim 2, said casing structure having a bore parallel to the cylinder axis, a pin displaceable in said bore, one of said inlet-valve closure members having an opening through which said pin at one end thereof is engageable by the adjacent one of said pistons, said pin having its other end engageable with 1 1. said other inlet-valve closure member, to keep said latter member in open position when said one piston abuts against said pin.

11. A lift and delivery pump comprising two coaxially aligned cylinders, a casing structure interposed between and fixedly joined with said two cylinders and having an inlet and an outlet for the medium to be pumped, two pistons axially displaceable in said respective cylinders and forming therewith respective cylinder chambers adjacent to said casing structure, a piston rod interconnecting said two pistons for conjointly reciprocating them in said cylinders, said casing structure forming separate inlet and outlet passages through which said two cylinder chambers are connectible with said inlet and outlet respectively, said outlet passage having two central mouths axially opposite each other at said respective cylinder chambers and traversed by said piston rod, said inlet passage having two arcuate mouths concentrically spaced from said central mouths at said respective cylinder chambers, said casing structure having two axially spaced inner valve seats extending around said respective central mouths and facing each other in the interior of said casing structure, and two outer valve seats surrounding said arcuate mouths and facing said respective cylinder chambers, outlet-valve closure means axially displaceable on said piston rod in the interior of said structure for selectively engaging said inner seats to close one of said respective cylinder chambers relative to said outlet, and two movable inlet-valve closure members disposed at the outside of said structure in front of said respective annular mouths for selectively closing said respective cylinder chambers relative to said inlet.

12. In a pump according to claim 11, at least one of said cylinders having adjacent to said casing structure an inner peripheral recess whose diameter is larger than that of the piston so as to form a peripheral shoulder, one of said inlet-valve closure members being axially displaceable in said recess and abuttable against said casing structure when in closed position and against said shoulder when in open position.

13. In a pump according to claim 11, said two cylinders being closed at their respective ends remote from said casing structure so as to form respective outer chambers behind said respective pistons, said piston rod being hollow and having openings in said two outer chambers to form a pressure equalizing communication between them.

14. In a pump according to claim 11, said two cylinders being closed at their respective ends remote from said casing structure so as to form respective outer chambers behind said respective pistons, duct means forming a communication between theouter chamber on one side of said casing structure and the inner chamber on the other side, and separate duct means forming a communication between said other outer and inner chambers.

15. In a pump according to claim 14, said piston rod having two separate longitudinal bores which form part of said respective duct means.

16. In a pump according to claim 11, said outlet-valve closure means comprising two valve disks engageable with said respective inner valve seats, a tubular spacer coaxially seated on said piston rodbetween said two disks and axially displaceable on said rod in tight relation thereto to be taken along by said rod, one of said outlet valve disks having a recess in its inner periphery, a connecting piece having one end joined with said spacer and extending through said recess toward one of said inlet-valve closure members, said latter member having radial stems, and said connecting piece having stop means for entraining said latter member through said stems toward the inlet-valve closing position.

17. In a pump according to claim 16, said stop means comprising two individual stops axially spaced from each other at the other end of said connecting piece, said two stops jointly straddling said inlet-valve closure member, whereby reciprocation of said piston rod causes entrainment of said inlet-valve closure member to open and closed positions respectively.

References Cited UNITED STATES PATENTS Klootwyk 10317 8 WILLIAM L. FREEH, Primary Examiner US. Cl. 'X.R. 

